Imported cryogenic cryogenic control valve design and selection method
Imported cryogenic cryogenic control valve design and selection method Imported soft sealed gate valve , imported electric ball valve , imported steam trap , imported stainless steel globe valve , imported pilot-type safety valve , imported steam pressure reducing valve The imported low-temperature cryogenic control valve adopts long-neck bonnet heat insulation and is equipped with multiple spring actuators, which has the advantages of compact structure, light weight, and good stability. The valve body adopts precision casting angle structure and the material is aluminum alloy, which has good low temperature resistance. The bellows seal ensures that the control valve does not leak in low temperature applications. It is widely used in metallurgy, air separation, oxygen, petroleum, chemical and other low temperature, cryogenic occasions. Especially for precise control of cryogenic gases, fluids (such as liquid oxygen, liquid argon, etc.) process parameters remain at a given value. Here, Xiao Bian and the internationally renowned brand Locke Locke of Germany, for example, explain the design and selection methods of the imported cryogenic cryogenic regulating valve. When the operating temperature of the regulating valve is much lower than the freezing point, specific precautions should be taken. In some cases, special structures must be used to meet the operating requirements. The main problem is the proper selection of structural materials, especially at low temperature operating conditions (to -101 °C). Cryogenic refers to production operations at temperatures below -101°C, when many additional factors are considered. When the temperature range is between -29°C and 101°C, special impact carbon steel is used for the parts subjected to pressure. When the temperature is between -29°C and 46°C, LCB carbon steel materials are generally used to reach -101°C. The use of 3.5% nickel steel, these valves are generally equipped with ordinary long neck upper valve cover, in this temperature range, the main purpose is to make the heat entering the system as much as possible, and to prevent the stuffing box part will not be too cold and Allow the upper part of the upper valve cover and the stem on the packing box to freeze. The conventional long-neck type upper valve cap is generally installed in a vertical position to reduce the heat transfer of the operating fluid itself. At cryogenic temperatures, the structural material now does not use carbon steel but uses austenitic stainless steel, bronze, and Monel. In such a temperature range, the operation of the regulating valve is generally to control the extremely cold gas and liquefied gas, often encountered: air, nitrogen, oxygen, hydrogen and helium. Now pay special attention to the structure of the long-neck upper valve cap. Even when the valve body material is bronze, the long-neck type upper valve cap is generally made of austenitic stainless steel to reduce heat transfer, and it is extremely important to pay attention to the fact that the liquefied gas cannot be trapped between the upper valve caps because of the continuous vaporization at the time of closing. Risk of high pressure. In all cases, the regulating valve must be strictly insulated. The process equipment piping and valves in the cold area of ​​the plant are often in cold boxes. In this case, the regulating valve has a particularly long upper valve cover which can be mounted in a horizontal position. The larger upper valve cover portion is made of stainless steel and protrudes from the cold box wall. In this way, the valve trim including the spool and the valve seat can be removed without involving the valve body, and the valve body can be welded in the system to reduce the leakage of the cold box itself. In general, when the cryogenic control valve is processed, especially during assembly, the requirements for cleanliness are more stringent. When choosing a lubricant, be aware that it can be used to prevent wear when assembling parts, many lubricants will solidify or become brittle, and there are many fluids that are completely unsuitable for flow. For this reason, many compounds have been developed for this application and have been used in large quantities. There are many other things that require special attention. For example, when adjusting liquid fluorine, it will spontaneously ignite upon contact with any hydrocarbon; when controlling oxygen, whether it is normal or deep cold, there are more general problems, except that it is in contact with certain impurities. With the possibility of self-ignition, oxygen can also support combustion, and in the event of a fire, the entire pipeline system will be burned. Most valve companies require degreasing of cryogenic control valves. 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